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Policy-based design enables custom error handling in scalar regula falsi.

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This commit is contained in:
Atgeirr Flø Rasmussen
2012-05-24 10:02:14 +02:00
parent 60ed946835
commit 288679ff3a
2 changed files with 59 additions and 29 deletions
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4
opm/core/transport/reorder/TransportModelTwophase.cpp
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@@ -168,7 +168,7 @@ namespace Opm
// }
int iters_used;
// saturation_[cell] = modifiedRegulaFalsi(res, smin_[2*cell], smax_[2*cell], maxit_, tol_, iters_used);
saturation_[cell] = modifiedRegulaFalsi(res, saturation_[cell], 0.0, 1.0, maxit_, tol_, iters_used);
saturation_[cell] = RegulaFalsi<>::solve(res, saturation_[cell], 0.0, 1.0, maxit_, tol_, iters_used);
fractionalflow_[cell] = fracFlow(saturation_[cell], cell);
}
@@ -541,7 +541,7 @@ namespace Opm
GravityResidual res(*this, cells, pos, gravflux);
if (std::fabs(res(saturation_[cell])) > tol_) {
int iters_used;
saturation_[cell] = modifiedRegulaFalsi(res, smin_[2*cell], smax_[2*cell], maxit_, tol_, iters_used);
saturation_[cell] = RegulaFalsi<>::solve(res, smin_[2*cell], smax_[2*cell], maxit_, tol_, iters_used);
}
saturation_[cell] = std::min(std::max(saturation_[cell], smin_[2*cell]), smax_[2*cell]);
mobility(saturation_[cell], cell, &mob_[2*cell]);

84
opm/core/utility/RootFinders.hpp
View File

@@ -46,14 +46,33 @@
namespace Opm
{
inline double regulaFalsiStep(const double a,
const double b,
const double fa,
const double fb)
{
ASSERT(fa*fb < 0.0);
return (b*fa - a*fb)/(fa - fb);
}
struct ThrowOnError
{
static double handleBracketingFailure(const double x0, const double x1, const double f0, const double f1)
{
THROW("Error in parameters, zero not bracketed: [a, b] = ["
<< x0 << ", " << x1 << "] f(a) = " << f0 << " f(b) = " << f1);
return -1e100; // Never reached.
}
static double handleTooManyIterations(const double x0, const double x1, const int maxiter)
{
THROW("Maximum number of iterations exceeded: " << maxiter << "\n"
<< "Current interval is [" << std::min(x0, x1) << ", "
<< std::max(x0, x1) << "]");
}
};
struct ContinueOnError
{
};
template <class ErrorPolicy = ThrowOnError>
class RegulaFalsi
{
public:
/// Implements a modified regula falsi method as described in
@@ -61,13 +80,13 @@ namespace Opm
/// solution of nonlinear equations"
/// by J. A. Ford.
/// Current variant is the 'Pegasus' method.
template <class Functor>
inline double modifiedRegulaFalsi(const Functor& f,
const double a,
const double b,
const int max_iter,
const double tolerance,
int& iterations_used)
template <class Functor>
inline static double solve(const Functor& f,
const double a,
const double b,
const int max_iter,
const double tolerance,
int& iterations_used)
{
using namespace std;
const double macheps = numeric_limits<double>::epsilon();
@@ -85,8 +104,7 @@ namespace Opm
return x1;
}
if (f0*f1 > 0.0) {
THROW("Error in parameters, zero not bracketed: [a, b] = ["
<< a << ", " << b << "] fa = " << f0 << " fb = " << f1);
return ErrorPolicy::handleBracketingFailure(a, b, f0, f1);
}
iterations_used = 0;
// In every iteraton, x1 is the last point computed,
@@ -97,9 +115,7 @@ namespace Opm
// cout << "xnew = " << xnew << " fnew = " << fnew << endl;
++iterations_used;
if (iterations_used > max_iter) {
THROW("Maximum number of iterations exceeded.\n"
<< "Current interval is [" << min(x0, x1) << ", "
<< max(x0, x1) << "]");
return ErrorPolicy::handleTooManyIterations(x0, x1, max_iter);
}
if (fabs(fnew) < epsF) {
return xnew;
@@ -144,13 +160,13 @@ namespace Opm
/// Current variant is the 'Pegasus' method.
/// This version takes an extra parameter for the initial guess.
template <class Functor>
inline double modifiedRegulaFalsi(const Functor& f,
const double initial_guess,
const double a,
const double b,
const int max_iter,
const double tolerance,
int& iterations_used)
inline static double solve(const Functor& f,
const double initial_guess,
const double a,
const double b,
const int max_iter,
const double tolerance,
int& iterations_used)
{
using namespace std;
const double macheps = numeric_limits<double>::epsilon();
@@ -237,6 +253,20 @@ namespace Opm
}
private:
inline static double regulaFalsiStep(const double a,
const double b,
const double fa,
const double fb)
{
ASSERT(fa*fb < 0.0);
return (b*fa - a*fb)/(fa - fb);
}
};
template <class Functor>